Mineral oil compositions and methods of suppressing foaming in oils



Patented Mar. 26, 1946 UNITED STATES PATENT OFFICE MINERAL OIL COMPOSITIONS AND METH- ODS OF SUPIRESSING FOAIWING IN OILS Herschel G. Smith, Wallingford, and Troy L. Pa., assignors to Gulf Oil Cantrell, Lansdowne, Corporation, Pittsburgh,

Pennsylvania Pa, a corporation of No Drawing. Application August 3, 1942, Serial No. 453,458

14 Claims.

ing is quite objectionable. For example, in lubrieating automobile gearing (in the gear box, and rear axle) foaming produced by the churning of the gears gives rise to excessive leakage and loss of lubricant past retainer rings, etc. Moreover, foaming seriously interferes with the proper functioning of the oil. Automobile gears such as 'thcse-usedin transmission and differential gear assemblies often operate at very high speeds, as well as under high tooth pressures; therefore they require a very good lubricant to prevent or retard excessive wear due to metal-to-metal contact, and foaming is undesirable. The lubricants employed are viscous oils, often containing a so-called extreme pressure agent to assist in maintaining an oil film between the teeth; sulfurized sperm oil being especially good. If the lubricant contains air dispersed through it, it lacks proper film forming properties. Moreover foaming oil is much less effective to conduct heat away from the working zone. These difficulties are often aggravated by the fact that some extreme pressure agents present in the oil actually increase the foaming characteristics of the oil composition.

Foaming is also objectionable in other situations; for example, during the pumping of oils, and in compounding oils with extreme pressure agents and other additives-in operation involving thorough agitation. Nearlyall petroleum oils foam to some extent under violent agitation. The more viscous the oil the greater the amount of foam and the longer it persists after agitation is stopped.

Among the objects of our invention are the provision of a method whereby foaming or frothing of oils as described is suppressed; and the provision of gear lubricants and other lubricating compositions which are characterized by freedom from tendency to foam or froth even under severe conditions.

We have discovered that foaming of petroleum oils, even under the most violent conditions described, can be suppressed or prevented by incorporating in the mineral oil a small proportion of certain amine salts of isoamyloctyl phosphate having the following formula:

wherein R. represents a substituent selected from the class consisting of methyl and ethyl groups and hydrogen.

For example, a small proportion of dimethylaniline isoamyl octyl phosphate having an ad- 'justed acidity equivalent toa pH value within the range pH 2 to 4 is most effective. Likewise. the diethylaniline and aniline salts of isoamyl octyl phosphate, respectively, are also excellent foam inhibitors.

In eneral, dissolving almost any additive in oil has a tendency to increase foaming more or less. Our new agents or compounds are remarkable in that they suppress foaming, even when present in small amounts, say 0.01 to 1.0 er cent by weight of the composition. They have no deleterious effect on the lubricant properties or other properties of the oil.

Our agents can be incorporated in all sorts of oils, to achieve the stated results. One particularly advantageous field of use is in gear lubricants for automobiles and the like. As stated, these lubricants are viscous and they contain extreme pressure agents or other additives; both of which facts make for heavy foaming. By dissolving a fraction of a per cent of our agent foaming is prevented. For example, such a gear lubricant, within the purview of our invention, has the following compositions (per cent by weight): Refined high-viscosity, lubricating oil Refined sulfurized sperm oil Dimethylaniline isoamyl octyl phosphate 0.01 to 1.0

Another field of use is in light (low viscosity) oils used in socalled fluid drives or in hydraulic drives. With these light oils (which are often of viscosity as low as SAE 10 grade) agitation may produce considerable foam, even though the foam subsides very quickly on ceasing agitation. Our new agents are also useful in cutting oils and indeed in any oil or oily composition, whether used as a lubricant or not, in which it is desired to prevent foaming.

so to 95.0 5 to 10.0

In preparing our new agents, the selected amine is reacted with isoamyl octyl acid ortho-phosph'ate to obtain the desired amine salt thereof; the pH of the reaction mixture being adjusted to within the range 2.0 to 5.5 in so preparing and recovering the amine salt. For example, dimethylaniline is brought into reaction with isoamyl octyl acid ortho-phosphate, and the pH of the reaction mixture is adjusted to within the range 2 to 4. With the theoretical molecular ratio of the two reactants, 1:1, the product is apt to be slightly too acid, with a pH below 2, and this is taken care of by using a slight excess of the dimethylaniline so that the molecular ratio is between 1:1 and 121.1. The reaction product is an oil-soluble, oily liquid and dissolving it in oils or oil compositions is very simple. Likewise, the amine salts obtained by reacting isoamyl octyl acid ortho-phosphate with aniline and diethylaniline, respectively, are oily liquids. They too readily dissolve in oils and oil compositions and can be easily incorporated and blended with mineral lubricating oils and lubricant compositions. The proportion of the agent to be dissolved in the oil or oil base depends on the viscosity of the oil, its ingredients, and the severity of the conditions of use. Ordinarily 0.01 to 1.0 per cent of the agent is employed; these amine isoamyl octyl phosphates being very effective agents for the present purposes.

Isoamyl octyl orthophosphate, is a brown, oily liquid, its specific gravity is 1.009 at 24/4 C., and its viscosity 210, 75 and 29 centipoises at 25,

to 3.0. The reaction product was an oily substance, readily soluble in mineral oils and having the following properties:

Gravity, API 7.4 Specific gravity, 60/60 F 1.0l9 Viscosity, SUV 100 F 468 Pour, F 50 As the dimethylaniline isoamyl octyl phosphate is substantially insoluble in water, the pH equivalent is measured by the following expedient. Normal butanol (which contains a small amount of water) is adjusted to exact neutrality, pH 7.0, and the sample is dissolved therein. The pH of the solution is then measured in the ordinary way as for aqueous solutions, by electrometric or colorimetric methods. The butanol appears to serve as a blending agent, for dissolving the sample in the water, so to speak.

It will be noted that the measured pH of the aminophosphate is low despite the fact that a slight excess of amine is present. This is because the reaction involves neutralizing a rather strong acid with a very weak base.

Moreover, traces of mono-, diand tribasic acids may be formed under the conditions of the 50 and 75 C. respectively. It is insoluble in water and soluble in mineral oils to the extent of 11.70 parts in 100 parts of oil at 20 C. The or- .thophosphate decomposes at 302 to 311 F. It has the structural formula:

h/CH 3 Our preparation, the reaction product of the above, has the probable formula:

The following example illustrates one advantageous way of preparing our foam suppressor:

Example I.One hundred and twenty-one pounds of dimethylaniline were added to an iron vessel equipped with an air lance and 281 pounds of isoamyl octyl ortho-phosphate were introduced over a period of One hour; the slow rate of addition being desirable to maintain the tem perature of the reaction mixture below 185 F. At the conclusion of this reaction, the temperature was 180 F., and the pH of the mixture was 2.0. A pH of 3.0 was desired; 12.0 pounds of dimethylaniline were added, which brought the pH? pH determination. At any rate, the results are as stated.

The following example illustrates the preparation of a, gear lubricant in accordance with the invention.

Example II.-A highly viscous, hi hly refined Pennsylvania oil was selected as the base, and in it was dissolved 0.04 percent ofthe oily reaction product of Example I. As shown in the following table the change in viscosity and in color by in corporation of the agent was negligible.

Straight oil Improved oil Gravity, -API 20. 6 26. 5 Viscosity, SUV

Color, NPA 4. 75 4. 75

To evaluate the foaming properties of the straight oil and the improved oil, samples (500 cc.) of the two oils were subjected to foam test No. 1 (described below). The results were as fol- It will be observed that the straight oil developed twice its volume of foam under the conditions of the test and that an appreciable volume of foam remained even after an hours standing;

. while the improved oil developed only a negligible amount of foam, which was all gone at the end of an hour.

Decreasing the percentage to 0.01 still leaves the oil much less susceptible to foaming than the straight oil.

The foam suppressor as stated can be added to compounded lubricants to prevent foaming thereof. It is compatible with most of the other types of improvement agents now employed and the amount required to prevent foaming in such compounded lubricants is relatively small and does not deleteriously affect the other properties of compounded lubricants. This is an important part of the invention, as certain of the agents employed to impart particular properties to lubricating oils have been found also to promote the foaming of the oil composition when agitated. By adding even traces of the present foam suppressor, such compounded lubricants become very resistant to foaming, even under drastic service conditions.

In making up compounded lubricants of this type it is advantageous to dissolve the aminophosphate in the oil first, as thereby foaming is prevented during the step of mixing in the extreme pressure agent or other additive. But so far as performance of the lubricant in service is concerned, the order of addition makes no difference.

The following example illustrates the properties of an extreme pressure gear lubricant prepared in accordance with the invention.

Example IIL-A conventional gear lubricant contains 92.5 per cent by volume of a highly refined, viscous Pennsylvania oil and 7.5 per cent of refined sulfurized sperm oil (Smith 8a Cantrell Patent 2,179,064). A similar lubricant prepared according to the invention contains these oils in proportions 92.46 and 7.5 per cent respectively and 0.94 er cent of the product of Example I.

The viscosity of the conventional lubricant was 1918 SUV at 100 E, '76? at 130 F., and

141.7 at 210 F. The viscosity oftheimproved lubricant was only negligibly different from this, and the same was true of the other character istics-gravity, viscosity, index, flash and fire tests, pour test, color, sulfur, copper strip tests, centrifuge test (for gravity-separable matter), and carbon residue. The neutralization of the new lubricant was 0.56 against 0.50 for the old. The surface tensions were nearly identical. The

Almen and 'Ilmken tests, indicative of the lubrieating value of. the oil, as secured on the compounded oil before the addition of the foam suppressing agent, were the same as the corresponding tests made after the addition of the indicated amount of this foam suppressor.

In other words, the characteristics of the two lubricants were practically the same, except for the foaming properties. The following are comparable tests (the nature of which is described in detail below) on these properties. The sam-- ples were 500 cc. each, the speed of the agitators 550 R. P. M. and the intial temperature 77 F.

To evaluate the foaming tendency of petroleum oils and compositions a test was devised which affords an exceptionally accurate indication of the comparative foaming tendencies. A sample of oil is subjected to very drastic foaming conditions under a standardized procedure which makes it possible to determine quantitatively the tendency of the oil to foam and the stability or permanency of the foam produced. In general it resembles a somewhat similar testing method employed by the General Motors Corporation for determining the foaming tendencies of gearing lubricants, but has been modified in the direction of greater accuracy and in order to make it possible to record more comprehensibig test data.

Foaming test (No. 1)

An agitating means is provided which is an adaptation of an ordinary commercial motordriven household miXera Sunbeam Mixmaster," Model 1, manufactured by the Flexible Shaft Company, Chicago, Ill. The device employed in. the test is the usual household model with two slight changes: the turntable of the usual household mixer is replaced by a rigid platform, and a cylindrical brass container having an inside diameter of '1 inches and an inside height of 4 inches is substituted for the usual household glass mixing bowl. The container is fitted with a; gage for measuring the depth of oil or oil and foam. therein before and after agitati'on.

The agitator device itself comprises a pair of motor driven heaters which are of the convex outside surface type as described in. U. S. Patent 2,161,881, each beater having a pair of blades of the type indicated and being so positioned with respect to each other that the two pairs of beater elements are at right angles and rotate in opposite directions in closely spaced, overiapping paths. In operating position, the heaters are perpendicular to the base of the mixer, asshownin Patent 2,161,881. In the present test they are centered in the container and the bottom of the beaters is spaced approximately inch from the bottom of the pan when the latter is positioned on the rigid platform. With 500 cc. of oil in thecontainer, the heaters are submerged in the initialoil sample only to a depth of of one inch. The heaters are rotated at a speed of 550 R. P. M. controlled within :10 R. P. M.

A- measured sample of 500 cc. (:5 cc.) of oil .1

is introduced into the container, the temperature of the sample is brought to 77 F. and the container is then placed in position and the beater elements lowered into operating position.

The motor is started and adjusted to the speed indicated above. The beaters agitate the oil and beat air into the sample. Agitation is continued for exactly 15 minutes.

The motor is now stopped, the heaters are removed from the oil, and any oil or foam adhering to the beaters is permitted to drain into the container, which takes one or two minutes.

The foam level is then immediately determined, and the temperature of the sample is measured. It is then possible to calculate the ratio of the volume of oil and foam to the volume of the original oil, with correction for any temperature changes.

The container is removed and allowed to stand quiet for one hour (measured from the time the stirring is stopped). The volume and tempera ture measurements are. taken again, and serve to indicate stability or permanence of the foam produced.

The test procedure may of course be varied, as for example by changing the size of the sample, the speed of agitation or the time of agitation, or by taking the final measurements at an earlier or later period. However, in the test referred to in the specific example above the procedure was precisely as indicated.

Test No. 2 is the same as test No. 1 except that agitation is continued for 44 hours instead of 15 minutes. (Longer periods of agitation may be employed if a still more drastic test is required.)

In some very low viscosity oils considerable foam may develop during agitation, which disappears very quickly when agitation is stopped. These conditions are found, for example, in marine turbine lubrication systems (which use light oils) at the point where returned oil is discharged violently into a reservoir. To evaluate foaming in such cases there is employed a third test No. 3, similar in all respect to test No. 1 except that the measurements of oil and foam are made while the motor is still running. The following example shows how a turbine oil treated according-to the invention behaves under such conditions. 7

Example IV.A highly refined Pennsylvania turbine oil was subjected to test No. 3. After 15 minutes agitation the oil plus foam measured 800 cc. as compared with 500 cc. for the original oil.

The same oil after treating with 0.01 per cent of dimethylaniline isoamyl octyl phosphate tested only 540 cc. for the oil plus foam.

In the foregoing examples, we have illustrated certain embodiments of our invention employing dimethylaniline isoamyl octyl phosphate which is an excellent and advantageous agent for the purposes of this invention. However, as described ante, we may also employ with advantage other amine salts of isoamyl octyl phosphate .prepared by reacting the acid phosphate ester The reaction product of this amine with isoamyl octyl acid ortho-phosphate has the following probable formula:

I I B 02115 CHs-CHr-JII-CHz-CH;

The above compound is an excellent agent for the present purposes.

The reaction product of this amine with isoamyl octyl acid ortho-phosphate has the probable formula:

The above amine salt is readily soluble in oils and is another excellent agent for the present purposes.

The two amine salts described above may be used in lieu of the dimethylamine isoamyl octyl Phosphate afihefim e si e uen e- Add tional embodiments of our invention are further illustrated in the examples given post which illustrate other advantageous ways of practicing our invention.

Example V.One hundred and forty-nine pounds of diethylaniline were added to an iron vessel equipped with an air lance, and 281 pounds of isoamyl octyl ortho-phosphate were introduced over a period of one hour; the slow rate of addition being desirable-to maintain the temperature of the reaction mixture below 185 F. At the conclusion of this reaction, the temperature was F. and the pH of th mixture was 2.0 A pH of 3.5 was desired; a further 15 pounds of diethylaniline were added, which brought the pH to 3.5. The reaction product was an oily liquid.

It was readily soluble in mineral oils.

As the diethylaniline isoamyl octyl phosphate is substantially insoluble in water, the pH equivalent is measured by the following expedient describedante in Example I. Here again, the measured pH of the aminophosphate is low despite the fact that a slight excess of amine is present.

The following example illustrates the preparation of a gear lubricant in accordance with our invention using the aminophosphate obtained in Example V.

Example VI.-A highly viscous, highly refined Pennsylvania oil was selected as the base, and in it was dissolved 0.04 per cent of the oily reaction product of Example V. As shown in the following table the change in viscosity and in color by incorporation of the agent was negligible.

To evaluate the foaming properties of the straight oil and the improved oil, samples (500 cc.) of the two oils were subjected to foam test No. 1 (described ante). The results were as fol- Decreasing the percentage to 0.01 still leaves the oil much less susceptible to fofining than the straight oil.

Further, this foam suppressor can also be added to compounded lubricants to prevent foaming thereof. It was compatible with most of the 5 other typesof improvement agents now employed and the amount required. to prevent foaming in such compounded lubricants is relatively small and does not deleteriously affect the other prop-L ertles of compounded lubricant. By adding even traces of dlethorlaniline' isoamyl octyl phosphate. such compounded lubricants become very resistant to foaming even under drastic service conditicms. 40

The following example illustrates th properties of one such extreme presure gear lubricant.v prepared in accordance with our invention.

.Emmple VIL-Ai modern gear lubricant contains 92.5 per cent by volume of a highly refined, viscous Pennsylvania oil and 7.5 per cent of refined monoester of a sulfurized fatty acid. A similar lubricant prepared according to the invention contains these oils in proportions 92.46 and 7.5 per cent respectively and 0.04 per cent of the product of Example V. The viscosity of the modern gear lubricant was 1920 SUV at F., 768 at F. and 141.8 at 210 F. The viscosity of the improved lubricant was only negligibly different from this, and the same was true of the other characteristic-gravity, viscosity index, flash and fire tests. pour test, color, sulfur, copper strip tests, centrifuge test (for gravity-separable matter), and carbon residue. The neutralization number of the new lubricant was 0.56 against 0.50 for the old. The surface tensions were near- 1y identical. The Almen and Timken tests, indicative of the lubricatin value of the oil. as secured on the compounded oil before the addition of the foam suppressing agent, were the same as the corresponding tests made after the addition 65 of the indicated amount of this foam suppressor.

In other words, the characteristics of the two lubricants wer practically the same, except for the foaming properties. The following are comparable tests (the nature of which is described in detail ante; see foaming test No. 1) on these Properties. The samples were 500 cc. each, the speed of the agitators 550 R. P. M. and the initial temperature 77 F. 7

Foam tests Old lubficant New lubricant After stirring for l5min 15 min 44hr. Temperature, F 84 83 83. gill-i-foail li lcfc 1,740...- 540 590.

0.0 0 com m.-. 3.48... 1.08. 1.18. After standing 1 hr. after stirring stopped Tempereturo,F 77 77 77. gruff-Ica n; .660 60 540.

o o 01 0am W 1.32... 1.90... 1.05. Natureoffoam Coarse None The above tests and data clearly show the superiority of our new lubricant containing diethylaniline isoamyl octyl phosphate.

The following example shows how a turbine oil can be improved according to our invention:

' Example VIII.-A highly refined. Pennsylvania turbine oil was subjected to test No. 3. After 15 minutes agitation the oil plus foam measured 800 cc. as compared with 500 cc. for the original oil.

The same oil after treating with 0.01 per cent of diethylaniline' isoamyl octyl phosphate tested only 540 cc. for the 011 plus foam.

The following example illustrates one advantage'ou's way of preparing another of our foam suppressors, namely, aniline isoamyl octyl phosphate: J

Example IX.--.Ninety-three pounds of aniline were, added to an iron vessel equipped with an 'air'lance and '281 pounds of isoamyl octyl ortho phosphate were introduced over a period of one hour; the slow rate of addition being desirable to maintain the temperature of the reaction mixture below 212' F. At the conclusion of this reaction, the temperature was 180 F. and the pH of the mixture was 2.0. A pH of 3.5 was desired; a further 9' pounds of aniline were added, which brought the pH to 3.5. The reaction product, was an 'oilyliquid. It readily soluble in mineral oil's.

As the aniline isoamyl octyl phosphate is substantially insoluble in water, the pH equivalent is measured by the following expedient. Normal butanol (which contains a small amount of water) is adjusted. to exact neutrality, pH==7.0, and the sample is dissolved therein. The pH. of the solution is then measuredin the ordinary way as for aqueous solutions, by electrometric or colorimetric methods. The butahol appears to serve as a blending agent for dissolving the sample'in waten'so to speak.

It. will be noted that the measured pH of this aminophosphate is low despite the fact that a slight excess of amine is present. This is because the reaction involves neutralizing a rather strong acid with a very weak base.

Moreover, traces of mono-, di and tribasic acids may be formed under the conditions of the pH determination. At any'rate, the results are as stated.

The following example illustrates the preparation of a gear lubricant in accordance with the invention:

Example X.-A highly viscous, highly refined Pennsylvania oil was selected as the base, and in it was dissolved 0.04 per cent of the oily reaction product of Example IX. As shown in the following table the change in viscosity and in color by incorporation of the agent was negligible.

To evaluate the foaming properties of' the Foam tests straight oil and the improved oil, samples (500 cc.) of the two oils were subjected to foam test 01d N b No; 1 (described ante). The results were as folbrim lows:

Afterstirringfor min-.. 15min.-. 44hr. Temperature, F 84 83 83. Composition Straight oil Improvedoil 15 Oil+foa1 n,cc 1,740.... 540 590.

Vol of oil+foam I VOLOO 3.4s- 1.08-

At en f firri g 9 m e After standing 1 hr. after stirring p 1 F 34 83 stop Volume ofoil and foam,cc 1,760 635 Temperature, T 77 77 77. Ratio 3.52 -0 0i1+foam,cc 660 500 540. After 1 hr. standing: Vol. of oiH-Iosm Tcmperature,F 77 77 l.32 1.00"--. 1.08. fitioiiiffilifliififfjjjjjjjj 1. 3% it 01mm Nature of foam Fine No loam The above tests and data clearly show the supeq lnatio Volume M011 andfoam riority of our new lubricants containing. aniline It will be observed that the straight oil developed more than twice its volume of foam under the conditions of the test and that an appreciable volume" of foam remained even after an hours standing; while the improved oil developed only a negligible amount of foam, which was all gone at the end of an hour.

a thare etese a t o 9&

still leaves the oil much'lesssusceptible to foaming than the straight 'ofl.

Likewise,'this foam suppressor, namely, aniline isoamyl octyl phosphate, can also be added to compounded lubricants to prevent foaming thereof. It is compatiblewlth most of the other types of improvement agents now employed and the amount required to prevent foaming in such compounded lubricant is relatively small and does not deleteriously affect the other properties of compounded lubricants. By adding even traces of aniline isoamyl octyl phosphate, such compounded lubricants become very resistant to foaming even under drastic service conditions.

The following example illustrates the properties of one such extreme pressure gear lubricant prepared in accordance with our invention.

Example XI.A modern gear lubricant contains92.5 per cent by volume of a highly refined, viscous'Pennsylvania oil and 7.5 per cent of refined monoester of a sulfurized fatty acid. A similar lubricant prepared according to the invention contains these oils in proportions 92.46 and 7.5 per cent, respectively, and 0.04 per cent of the product of Example 12!.

' The viscosity of the modern gear lubricant was 1918 SUV at 100 F., 768 at 130 F. and 141.8 at 210 F. The viscosity of the improved lubricant was only negligibly different from this, and the same was true of the other characteristicsgravity, viscosity index, flash and fire tests, pour test, color, sulfur, copper strip tests, centrifuge test (for gravity-separable matter), and carbon residue. The neutralization number of the new lubricant was 0.56 against 0.50 for the old. The surface tensions were nearly identical. The Almen and Timken tests, indicative of the lubricating value of the oil, as secured on the compound oil before the addition of the foam suppressing agent, were the same as the corresponding tests made after the addition of the indicated amount of this foam suppressor.

isoamyl octyl phosphate. 1

The following example shows how a turbine oil can be improved according to our invention, using aniline isoamyl octyl phosphate as the.improvement agent or foam suppressor.

Example XII.A highly refined Pennsylvania turbine oil-was subjectedtotest No. 3; After 15 minutes agitation the oil plus foam measured 800 cc. as compared .with 500 .cc..for..the.original.

oil. 1

The same oil after treating with 0.01 per cent wherein R represents a methyl or ethyl group. This class of compounds is readily soluble in mineral oils and lubricants and are exellent foam suppressors. Their use in mineral lubricating oils and compounded lubricants has been fully illustrated ante.

While our invention has been described above with reference to various specific examples and embodiments, it will be understood that the invention is not limited to such illustrative examples and embodiments, but may be variously practiced within the scope of the claims herein made. This application is a continuation-in-part of our prior application Serial No. 421,842, filed December 5, 1941. The aromatic amine salts of isoamyl octyl orthophosphate herein disclosed are new chemical compounds which are claimed per se in our continuing application, Serial No. 639,- 701, filed January '7, 1946.

What we claim is:

1. A mineral oil composition resistant to foaming, comprising mineral oil and a small proportion of dimethylaniline isoamyl octyl orthophosphate exhibiting a pH value between approximately 2 and 4. p

2. The composition of claim 1 wherein the proportion of said orthophosphate is between 0.01 and 1.0 per cent by weight of the composition.

3. A mineral oil resistant to foaming comprising a small proportion of the reaction product of dimethyl-aniline and isoamyl octyl orthophosphate, said reaction product being an oily oil-soluble liquid and having an acidity equivalent to a pH value between 2 and 4.

4. A method of making mineral oil compositions which are resistant to foaming, which comprises incorporating in a mineral oil composition a small proportion of dimethylaniline isoamyl octyl phosphate, of pH value in the range 2 to 4.

5. A method of suppressing foaming of mineral oils and oil compositions which comprises incorporating and maintaining therein during use a small proportion of dimethylaniline isoamyl octyl phosphate of pH value in the range 2 to 4.

6. A mineral oil com-position resistant to foaming, comprising mineral oil and a small proportion of an amine salt of isoamyl octyl phosphate having the formula wherein R represents a substituent selected from 9. The composition of claim 6 wherein said amine salt is diethylaniline isoamyl octyl phosphate.

10. The composition of claim 6 wherein said amine salt is dimethylaniline isoamyl octyl phosphate.

11. A mineral oil composition resistant to foaming, comprising mineral oil and a small proportion of a dialkylaniline salt of isoamyl octyl phosphate having the formula:

.wherein R represents a substituent selected from the class consisting of methyl and ethyl groups.

14. A mineral oil resistant to foaming, comprising a small proportion of a reaction product of isoamyl octyl orthophosphate and an amine having the following formula:

wherein R represents a substituent selected from the class consisting of methyl and ethyl groups and hydrogen, said reaction product being an oily liquid readily soluble in mineral oil.

I-IERSCHEL G. SMITH. TROY L. CANTRELL. 

